P2138

Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation

Car Fault Codes Fuel & air

Can you still drive? With care, short trips only

Who can fix it? Needs a workshop

Typical repair time 30 minutes – 1.5 hours

Typical cost SAR 100 to 900

What it means

On most vehicles, sensors D and E are the two accelerator pedal position sensors. The engine computer constantly compares their signals and has found that they do not agree, so it no longer trusts the driver's request and enters limp mode with limited power.

Symptoms4

Check engine light on, sometimes with the electronic throttle warning light.
Weak acceleration and limp mode.
Delayed or intermittent accelerator response.
Engine held at idle in some cases.

Possible causes5

Worn track in one of the sensors inside the pedal assembly at a certain position.
Corroded or loose pedal sensor connector.
High resistance in the ground or reference wire of one sensor.
Chafed wiring near the pedal from repeated movement.
Engine computer (ECU) fault, which is rare.

How to diagnose5

Read all stored codes; single-sensor codes such as P2122 or P2127 identify the faulty sensor.
Watch the D and E signals on a scan tool while pressing the pedal slowly, and look for a jump, dropout or change in the ratio between them.
Inspect the pedal sensor connector for corrosion or loose pins.
Measure the reference voltage and ground for each sensor and compare them with the manufacturer specification.
Wiggle the wiring near the pedal while watching the readings.

How to fix5

Clean or repair the connector.
Repair chafed or broken wiring.
Repair a ground or reference wire with high resistance.
Replace the pedal sensor or the complete pedal assembly.
Clear the codes, perform a relearn if the manufacturer requires it, and confirm the code does not return.

Repair cost

0–500

500–2,000

2,000–5,000

5,000+

In Saudi riyals; the highlighted part is the expected range for this fault.

The cost is low for a connector or wiring repair, and rises when the pedal assembly is replaced, which is the most common fix for this code.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions

What is the difference between P2138 and P2135?

P2138 usually concerns the two accelerator pedal sensors, while P2135 concerns the two throttle position sensors in the throttle body. Both mean the two signals disagree.

Can I drive with this code?

Carefully and only a short distance to a workshop, since power is limited and pedal response may lag.

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This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.

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